Tag: metals

Questions Related to metals

Potassium on exposure to air gives:

chemistry metals physical properties of metals and non-metals some physical properties of metals general characteristics and uses of metals

  1. Potassium peroxide

  2. Potassium superoxide

  3. Potassium dioxide

  4. Potassium oxide

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Correct Option: A,B,D
Explanation:

Potassium is an extremely active metal that reacts violently with oxygen in air. Potassium oxidizes faster than most metals and forms oxides with oxygen-oxygen bonds. Three species are formed during the reaction: potassium oxide, potassium peroxide, and potassium superoxide.

$8K + 4O _2 \rightarrow 2K _2O + 2KO _2 + K _2O _2$

Four metals $P$, $Q$, $R$ and $S$ react with water as given below:
I. $P$ reacts with cold water
II. $Q$ reacts with hot water
III. $R$ reacts with steam
IV. Red hot $S$ reacts with steam.
Then, highly reactive metal is:

chemistry metals physical properties of metals and non-metals some physical properties of metals general characteristics and uses of metals

  1. $P$

  2. $Q$

  3. $R$

  4. $S$

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Correct Option: A
Explanation:

The highly reactive metal is $P$ as it reacts with cold water. This is because, the reaction with cold water requires lowest energy of activation.

Select the object from the following which can shine (have lusture) _____________

chemistry metals physical properties of metals and non-metals some physical properties of metals general characteristics and uses of metals

  1. glass bowl and wooden bowls

  2. towel and toys

  3. shirts and scarfs

  4. ornaments and brass utensils

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Correct Option: D
Explanation:

1) ornaments and brass utensils both are made up of metals.

2) Metals are lustrous because of the free electrons they have.

3) The free electrons can move freely in the metal causing any light incident on them to get reflected back.

4) This reflection is specular reflection rather than diffused and thus the metal surface appears shiny or lustrous.

Metallic radii of some transition elements are given below. Which of these elements will have the highest density?
Element                    $Fe$     $CO$       $Ni$     $Cu$ 
Metallic radii/pm     126     125     125    128

chemistry metals physical properties of metals and non-metals some physical properties of metals general characteristics and uses of metals

  1. same 

  2. $Ni$

  3. $Co$

  4. $Cu$

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Correct Option: D

Which one of the following four metals would be displaced from the solution of its salt by other three metals?

chemistry metals physical properties of metals and non-metals some physical properties of metals general characteristics and uses of metals

  1. Mg

  2. Ag

  3. Zn

  4. Cu

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Correct Option: B
Explanation:

Ag metal would be displaced from the solution of its salt by Mg, Zn or Cu metals.

Among the given metals, the standard reduction potential for the half reaction $\displaystyle Ag^+ + e^- \rightarrow Ag$ is maximum.

Hence, among the given metals (ions),  $\displaystyle Ag^+ $ ion has maximum strength as oxidising agent. Hence, $\displaystyle Ag^+$ ion gains an electron and other metals loses electron.

Read the following statements and answer as true or false.
The presence of carbon in pig iron makes it brittle.

chemistry metals physical properties of metals and non-metals some physical properties of metals general characteristics and uses of metals

  1. True

  2. False

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Correct Option: A
Explanation:

 Pig iron has a very high carbon content, typically 3.8–4.7%, along with silica and other constituents of dross, which makes it very brittle, and not useful directly as a material except for limited applications.

Which of the following is not correct observation based on Ellingham diagram?

chemistry metals physical properties of metals and non-metals some physical properties of metals general characteristics and uses of metals

  1. A metal can reduce the oxide of other metal which lies above it in Ellingham diagram

  2. $CO$ is more effective than $C$ as reducing agent below $170^{o}C$

  3. $\Delta G^{o}$ metal oxide is higher than of $CO _{2}$ hence oxidation of metal sulphides to oxides is not favourable

  4. Need for conversion of metal sulphide to metal oxide before reduction can be explained thermodynamically

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Correct Option: A
Explanation:

As moving down of bottom of diagram metals becomes more reactive oxides will be hard to reduce.A given metal can reduce the oxides of other metal which lies above it in Ellingham diagram.

Which of the following are properties of non-metals?

chemistry metals physical properties of non-metals uses of metals and non metals physical properties of metals and non-metals

  1. Lustre

  2. Can form alloys

  3. Amorphous

  4. Non-conductive towards electricity

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Correct Option: C,D
Explanation:

The properties of non-metals are:

  1. They are amorphous in nature.
  2. They are not malleable and ductile.
  3. They are poor conductors of heat and electricity.
  4. They do not form alloys.

Non-metal that has a metallic lustre and sublimes on heating is : 

chemistry metals physical properties of non-metals uses of metals and non metals physical properties of metals and non-metals

  1. chlorine

  2. bromine

  3. oxygen

  4. iodine

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Correct Option: D
Explanation:

Iodine is an intensely colored solid with an almost metallic luster. This solid is relatively volatile and it sublimes when heated to form a violet-colored gas.

Which non-metal has a shining surface?

chemistry metals physical properties of non-metals uses of metals and non metals physical properties of metals and non-metals

  1. Graphite

  2. Phosphorous

  3. Sulphur

  4. None of the above

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Correct Option: A
Explanation:

Graphite is the most stable form of carbon and so it is used as the standard state for defining the heat and formation of carbon compounds. It has a layered planar structure and the bonding between the layers is vander waals bonds. It is a non metal with shining surface.